Automated handling system for container held material

ABSTRACT

A load bed is moved relative to a rack that stores material placed in containers or pallets. A control unit is provided to guide the bed to a preselected container position and electromagnetic means attached to the bed attracts the container onto the bed. The bed is then returned to an initial station where the container can be retrieved. The reverse process is employed to return the container in the rack. Similarly, fork members can be employed, in lieu of the electromagnetic means, to handle pallets.

[ Jan. 1,1974

Patent 1 1 United States Doran et a1.

mam u m m u Hn mm mm "g r. lrle l mmmm S w awm SACCK 99002 66777 9999911111 72 97 00966 68 22 ,3 1 55067 58927 1 33333 o N m.

[ 1 AUTOMATED HANDLING SYSTEM FOR CONTAINER HELD MATERIAL [76]Inventors: John T. Doran, 3707 Bradley Ln ABSTRACT A load bed is movedrelative to a rack that stores maployed to e container in the rack.Similarly, fork mem- 2 Claims, 12 Drawing Figures th bers can beemployed, in lieu of the electromagnetic means, to handle pallets.

Primary Examiner-Gerald M. Forlenza Assistant ExaminerR. B. JohnsonAttorney-Morris Liss et al.

terial placed in containers or pallets. A control unit is provided toguide the bed to a preselected container position and electromagneticmeans attached to the bed attracts the container onto the bed. The bedis then returned to an initial station where the container can beretrieved. The reverse process is em return AA 66 NH M m2 PATENTEUJANH974 3.782.565

SHEET 1 OF 5 F/G. 1 1o M wgw fiTTOFA/EVS AUTOMATED HANDLING SYSTEM FORCONTAINER HELD MATERIAL FIELD OF THE INVENTION THE PRIOR ART Automatedretrieval and storage handling systems have been known for some time.With the advent of solid state logic circuitry, systems can beconstructed to sense a particular container location and retrieve orreturn a container thereto from a movable bed.

In one prior art system, prefabricated racks and containers of the samesize are employed to store parts in a warehouse. A cable drive connectsa motor with a movable bed and control means cooperate with the bed tomove the latter to a preselected container location. Photoelectricsensing is employed to detect the exact container placement. Pulsecounters detect coincidence between preselected container locationcoordinates and the corresponding location in the rack.

Because this prior art system relies upon cable drive, it is not capableof handling relatively heavy loads. Further, the requirement thatparticular racks and single sized containers be used presents aneconomic burden to a potential user who finds it necessary to dismantleand remove his existing rack system.

The prior art system is able to operate along three axes. The X and Yaxes represent vertical and horizontal coordinates in a particular rack.The Z-axis defines the direction between adjacent racks separated by anaisle. Thus, although the prior art system is able to retrieve and storecontainers across both sides of an aisle, the system requires the racksand containers to be identical in structure and mirror images as far aslocation is concerned.

SUMMARY OF THE INVENTION The present invention is a storage andretrieval automated system incorporating a movable bed that is capableof operating along three axes. Material to be stored and retrieved isplaced in containers or bins, the containers being stacked in a rack. Alogic control unit is provided to allow the selection of a particularcontainer location which permits the machine to move to the selectedlocation and either retrieve or return a container thereat. Sensors areprovided along the X and Y axes. The logic control unit counts thesensors along the X- axis until coincidence is detected with thepreselected X coordinate. At the same time, this operation is performedwith respect to the Y-axis. As a result of coincidence, the machine bedis positioned adjacent the proper container location. During retrieval,an electromagnetic means mounted on the bed is moved to magneticallyengage a selected container. Then, the electromagnetic means pulls thecontainer onto the bed. Once this is accomplished, the bed is moved to astation where the container can be removed. The reverse process isperformed when a container is to be returned to its original location inthe rack.

By placing racks in spaced relation to one another across an aisle, thebed is capable of selecting containers on either side of the aisle. Thisallows the bed to operate along a Z-axis in both directions.

The primary object of the present invention resides in the adaptabilityof the present automated system to existing rack installations. I

A further object of the invention is to present an automated systemcapable of storing and retrieving differently sized containers or bins.

Still further, the present invention may operate with rack installationson opposite sides of an aisle without the requirement that the containerlocations on oppo-- sitely disposed racks be mirror images.

Yet another advantage of the present invention is derived from themechanical drive employed. Rather than utilizing a cable drive, thepresent invention includes a heavy-duty rack and pinion drive.Accordingly, heavier loads can be handled than in systems employingcabledrive.

Other objects, features and advantages will appear from the followingmore detailed description of illustrative embodiments of the invention,which will now be given in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view ofthe present system particularly illustrating the drive means for thesystem.

FIG. la is a partial sectional view of the system taken along sectionline 1a lain FIG. 1 which illustrates means for securing a movable frameto a stationary rack system.

FIG. lb is a partial section view taken along line 1b 1b in FIG. 1illustrating the means for mounting a load bed to a frame.

FIG. 2 is a perspective view of the present system when operating.

FIG. 3is a block diagram of the electrical circuitry for locating thesystem relative to a desired container location.

FIG. 4 is a block diagram of the logic control circuitry for the system.

FIG. 5 is a sectional view illustrating a fail-safe braking device.

FIG. 6 is a block diagram of the circuitry for actuating the fail-safebraking device.

FIG. 6a is a time diagram of the signal generated from anelectromagnetic pick up component of the failsafe circuitry.

FIG. 7 is a logic diagram of an anti-bounce circuit used in the presentinvention.

FIG. 8 is a timing diagram for the logic diagram of FIG. 7.

FIG. 9 is a block diagram of a Span system employed in the presentinvention.

DESCRIPTION OF THE INVENTION Referring to the figures and moreparticularly FIG. 1 THEREOF, THE MECHANICAL STRUCTURE OF A DRIVINGMECHANISM IS ILLUSTRATED. This mechanism causes a loading platform orbed to become positioned adjacent a selected container that is stored ina rack. Reference numeral 1% generally indicates a rectangular openframe which serves as the central structural support for a bed orplatform to be discussed hereinafter. The frame 16 is capable ofhorizontal movement to and fro along an X-axis.

In order to allow motion in the vertical direction or Y-axis, rack gearsT2 are suitably attached to the vertical legs of the frame 10. Thesegears mesh with pinion gears 14 and 16 that are interconnected by ashaft 18. The loading bed or platform 19 is suitably journaled to theshaft 18 and rides along with it to a particular Y- coordinate. When thebed W is to assume a particular X-coordinate, the entire frame lit)moves in the horizontal direction until the X-coordinate is attained.Inasmuch as the bed 19 is mounted to the frame 10, the bed will likewiseattain the X-coordinate. Once the preselected X and Y coordinates of thebed 19 result, the bed is at a preselected location with respect to acontainer thereby permitting the bed 19 to store or retrieve thecontainer as explained in greater detail hereinafter.

In order to rotate the shaft 1% and cause commensurate motion of thepinion gears 14 and 16, a sprocket wheel 20 is mounted to the shaft 38through a slip clutch 22. When the sprocket is caused to rotate, thiswill force linked rotation of the shaft 118 and the pinion gears M and16.

The sprocket wheel 20 is caused to rotate by a transmission systemincluding an electric motor 24 having its output shaft connected to atransmission box 26. The output shaft of the transmission box drives asprocket wheel 2% that entrains a chain 30. The opposite end of chain 30drives the sprocket wheel 20. The motor 24 is reversible therebypermitting both upward and downward movement of the bed 19 relative tothe frame 16. The motor 24 and transmission box 26 are permanentlymounted to the bed 19.

Similar drives exist adjacent the vertical legs of frame 110. Morespecifically, pinion gears 42 and 44 mesh with the rack gears 34 and 32,respectively. The shaft 46 is connected between the pinion gears 32 and44 and is suitably journaled to the frame 10. Likewise, pinion gears 36and 38 mesh with rack gears 34 and 32 respectively. An interconnectingshaft 46 is journaled to the frame. Shaft 46 drives the frame whileshaft 46 serves as a driven member. When the shafts rotate, frame Ml,journaled to the shaft, will undergo horizontal movement along theX-axis. A chain drive accomplishes this function. As will be seen inFIG. l, a motor 48 attached to frame 116 has its output shaft driving atransmission box 50 which is likewise attached to frame 10. A sprocketwheel 52 is attached to the drive shaft of the transmission box 50 andentrains one end of a chain 53. The opposite end of the chain entrains asprocket wheel 54 which is connected to shaft 46 through a slip clutch56. Rollers 58 are mounted to the lower leg of frame 16 and are adaptedto ride along track 60 which may be connected to the floor or a lowerportion on a rack system.

A channel iron 62 is attached to a rack system and is positioned aboverack gear 34, the channel iron 62 being parallel to the rack gear 34.Pinch rollers 64 and 66 are connected to the left and right verticallegs of frame 10, respectively. These pinch rollers engage channel iron62 which is fixed to a rack system. The engagement between pinch rollersand the channel iron prevents the frame from tipping forwardly.

A view of the present system relative to a rack installation withcontainers or bins stored therein is illustrated in FIG. 2. The loadingbed for retrieving and returning the containers to storage is generallyindicated by reference numeral 19. An electromagnetic unit 70 ispositioned on top of the bed 19 and is movable along a third orthogonalZ-axis. A slot track 72 is formed in the bed 19 to guide Z-axisdisplacement of the electromagnetic unit 70. The slot 72 extends alongthe entire Z dimension of the bed to permit the electromagnetic unit 70to operate upon containers stored in racks on both sides of an aisle.The previously discussed motor 24 and transmission box 26 are mounted tothe bed 19, under the electromagnetic unit 70. The previously discussedmotor 48 and transmission box 50 are secured to the right vertical legof the frame as illustrated in FIG. 2. A typical container 73 has amagnetic plate 74 suitably attached to an outward end thereof. it is theplate 74 which is attracted by the electromagnetic unit 70 after the bedW is positioned in line with the plate 74. Upon actuation of a controlunit to be discussed hereinafter, the electromagnetic unit 76 movesalong slot 72 until magnetic contact is made with the magnetic plate 74.Subsequent to the contact, the electromagnetic unit 70 draws thecontainer 73 onto the bed 19. Afterwards, the frame supported bed 19 isreturned to a home or original station. It should be explained that theX and Y coordinates of the bed are adjusted simultaneously. Therefore,as the bed moves along horizontally, it also undergoes verticaldisplacement until preselected coincidence occurs between the bed 19 andchosen X, Y coordinates. The bed 19 will then move to the chosen left orright side of an aisle (Z coordinate A control unit generally indicatedby reference numeral 76 is permanently mounted to the frame and controlsthe entire operation of the system. As explained in greater depthhereinafter, thumb switches are provided to enter the location of adesired container. Thereafter, the control unit 76 initiates X and Ymotion of the bed 19 until the bed becomes aligned with the location ofa container that corresponds with the location entered with the thumbswitches on control unit 76. Thereafter, the control unit 76 controlsthe motion of the electromagnetic unit 76 to effect retrieval-storageoperation, the control unit 76 causes the frame supported bed 19 toreturn to a home station.

At this point, the basic mechanical operation of the system has beenexplained. Accordingly, the following discussion will concentrate uponthe electrical portion of the system.

FIG. 3 illustrates in block form the system portion that effectsprecision movement of the load bed between a home station and aparticular container location.

in FIG. 3, a position locator in the form of a thumb wheel switch 78 isrepresented for manually entering a container position location. Adecimal number is set which corresponds to XYZ coordinates of a selected.container location. For example, the switch may be of duplicated forboth the X and Y axis. However, for.

convenience, the system portion involved with only the X-axis will beexplained. The counter b2 counts in BCD and is initially triggered byproximity switches 84 and 85. The proximity switches may be of anysuitable conventional design. However, by way of example, the proximityswitches may be of the magnetic sensing type which generates anelectrical output as it is swept by a magnet. The output of theproximity switches 84 and 85 are fed into an anti-bounce circuit 86which prevents spurious generation of signals from the proximityswitches that might cause actuation of the counter 82. An output line 87connects the anti-bounce circuit 86 to an input of the counter 82. Uponmovement of the present system along incremental distances on the X-axis, electrical signals will be generated by the proximity switch 84 asincrementally spaced magnets on a rack system are passed. As will becomelater apparent, switches 84 and. 85 are respectively associated with theleft or right directions along the Z-axis. Thus, when for example theleft side of an aisle is selected the output of switch 84 is transmittedto the anti-bounce circuit 86 because gate 84 is actuated. Similarenablement occurs for the switch 85 through gate 85 when the right sideof the aisle is selected.

A chosen container location will have a preselected X coordinate. As thecounter 82 increments upwardly, there will come a time when the count inthe counter 82 will coincide with this desired X coordinate which hasbeen set by the thumb wheel switch 78. The coincidence is detected bycomparator 80. During periods when coincidence is not detected, thecomparator 80 issues an output signal along lead 89 which feeds a driveTRIAC 88 or S.C.R. switch. The output of the TRIAC- feeds a motorstarter 90 via lead 91. The motor starter may be of the relay typeenabling relatively small control currents to actuate a reversible motor92 that is energized by the motor starter 91) via lead 93. Whencoincidence is detected by the comparator 80, energization of TRIAC 88ceases thereby causing the motor 92 to stop. 7

Referring to FIG. 2, permanent magnets 102 are mounted along the strips98 and 100 in parallel relation. The magnets along each strip actuate acorresponding proximity switch 8d or 85. It is to be noted here that themagnets 102 are stationarily mounted with respect to frame and areadapted to detect motion of bed 19 in the vertical direction (along theY- axis). The proximity switches 84, 85 for detecting bed displacementin this direction would be mounted at points 104 and 106 therebysecuring the proximity switches to the bed and in proximity with themagnets 102 when the bed moves vertically upwardly on the frame 111 pastthe magnets 1112.

A similar structure is involved in detecting passage of frame 10 alongthe horizontal or X-axis. Thus, vertically spaced parallel strips 110and 112 are fastened to channel iron 62. Spaced permanent magnets 114and 116 are secured to the strips 110 and 112, respectively. A bar 118is horizontally positioned between the vertical legs of frame 11).Spring loaded, free floating proximity switches 120 and 122 correspondto the proximity switches 84 and 85 shown in FIG. 3 previously explainedin connection with X-axis operation. The switches 120 and 122 will beselectively operated depending upon which side of an aisle (Z-axis) thesystem is to operate along.

FIG. 4 indicates in block form the circuitry which functions as a logiccontroller or operation sequencer. Referring to the figure, a counter124 is provided. This counter may for example be a Logic Johnson RingCounter. The output of the ring counter includes a plurality of leadswhich drive a decoder 126 through gate circuitry 127 to be elaboratedupon hereinafter. The decoder is of a conventional logic type which iscapable of generating unique operation codes along its output lines. Afirst output line 128 is an X-Enable which is employed as an input to agate 146 (FIG. 3) that serves to control, along with comparator 811),actuation of the drive TRlAC 88. If the control circuitry of FIG. 3 wereused to drive the system in the vertical direction (Y- axis), a Y-Enablewould be substituted for the X- Enable. The Y-Enable line is indicatedby reference numeral 130 in H6. 4. A third output line 136 carries aZ-Enable which is generated to selectively enable gates 84 or 85' ofFIG. 3. This, as previously mentioned, will determine which side of anaisle (Z-axis) the system will operate upon.

As previously explained, and as will be appreciated by viewing FIG. 2,after the load bed 19 rests before a selected container, theelectromagnetic unit is moved from its central position on the bedtoward the rack system. During retrieval, the electromagnetic unit 70becomes magnetized as it moves toward engagement with a selectedcontainer. This action of the electromagnetic unit is controlled by themagnetizing control line 132 (FIG. 4). An additional output line of thedecoder is referenced by 134 and carries a demagnetizing control signal.In a retrieval situation, after the electromagnetic unit 70 has engageda pre-selected container and pulls it onto the bed under the force ofmagnetic action, the electromagnetic unit 71) becomes demagnetized aftera control signal on line 134 appears. Each of the output control lines128, 130, 132, 134 and 136 are connected in parallel by transmissionlines 140 to a sequence updater 138. Reply lines 142 are connected tocomparator 80 (FlG. 3) for the X-axis and to a similar comparator forthe Y-axis. When there is coincidence of signals on reply lines 142 andtransmission lines 140., the sequence updater 138 generates a signal 144which is fed back to the Logic Johnson Ring Counter 124, in closed loopfashion, to update the counter. By way of explanation, the ring counter12 1 maintains unique states because each time the counter progresses, a0 is counted out each time a l is counted in.

Referring in FIG. 4 to the gating circuitry 127, it will be observedthat the ring counter 1241 has True and Compliment lines respectivelyfeeding gates 1 18 and 150. Each of these gates is connected to anenabling circuit referred to as a span multiple locating circuit 152, tobe explained hereinafter. However, it should suffice at this point toindicate that the ring circuit 124 drives the decoder 126 incrementallyto perform X- Enable, Y-Enable, Z-Enable, Magnetize and Demagnetize.

Returning to the span multiple location circuit 152 (FIG. 4), thiscircuitry is adapted to permit the load bed to move to a second selectedcontainer position if photo-electric sensing means 153 (HO. il) indicatethe absence of a container at the first selected container position. Inoperation of the present system, when the True line is enabled throughgate 14%, the decoder functions to initiate movement of the load bed toa first selected position. When the absence of a container at thatposition becomes manifest, the Compliment line becomes enabled throughgate 11l thereby indicating to the system that a Span operation is tocommence by renewing energization of the X-axis motor which initiates anew retrieval cycle. The span circuit 152 controls the selection ofeither gate 148 or 150. In actual practice, the load bed will move tothe next container location on the X-axis, if an appropriate thumb wheelswitch is actuated in the ring counter 124. Again, this occurs when thecompliment of the counter 124 is read into the decoder 126.

FIG. represents a fail-safe system for preventing the load bed fromdescending rapidly in the event power failure occurs.

Referring to FIG. 5, a permanent magnetic cyclinder is indicated by 154.At one end of the cylinder is a brake plate 160 that is rotatable withrespect to the central cylindrical portion. The brake plate 160comprises a number of pie-shaped ferro-magnetic strips 156. Anelectromagnet 158 is mounted within the cylindrical structure 154. Thiselectromagnet serves as a bucking magnet to defeat the normally existingholding or braking power of the permanent magnet brake plate 160. Tofully appreciate the fail-safe brake, consider the relatively large gear162 connected to shaft 171, theleft end of the shaft being fixed to thebrake plate 160. The large gear 162 meshes with a smaller gear 164 thatis mounted on its own axis 165. The small gear 164 in' turn meshes witha relatively larger gear 166 that is in turn secured to an axially fixedshaft 170. The outer end of shaft 170 securely mounts a sprocket wheel168 that engages a sprocket chain 172. The chain extends verticallyalong the right leg of frame as shown in FIG. 2. The upper end of thechain is fixed at point 174 to the top of the frame 10 while the lowerend 176 of the chain is fixed to a lower point on the frame 10. Duringnormal operation of the device, the electromagnet 158 is energized onlines 177 by circuitry to be discussed hereinafter. Energization of thiselectromagnet presents a bucking magnetic field which defeats themagnetic action of the brake plate 160 relative to the cylindrical body154 which is attached to the bed as indicated by 179. This permitsrotation of the brake plate 160 and commensurate rotation of shaft 171which in turn allows rotational operation of the gear train 162, 164,166, 168 and the chain 172. However, in the event there is a failurefollowed by rapid load bed descent, the energization of lines 177terminates thereby terminating energization of the electromagnet 158.When this occurs, the brake plate 160 has complete dominance and causesmagnetic attraction of the plate 160 toward the cylindrical body 154followed by frictional engagement with an internal friction plate 181which results in rotational termination of the brake plate 160.

Inasmuch as the previously discussed gear train is linked with the brakeplate 160 through its shaft 171, this gear train likewise ceases torotate. As a result, there is no further motion between the sprocketwheel 168 and the chain 172. Accordingly, the cylindrical body 154remains vertically stationary. Because the cylindrical body 154 isattached to the load bed at 179, the load bed likewise remainsvertically stationary thereby preventing descent of the load bed duringa power failure.

In order to appreciate the generation of control signals on lines 177,further reference is made to FIG. 5 wherein an electromagnetic pickup178 is illustrated in proximity with the gear teeth on the gear 162. Theelectromagnetic pickup 178 senses the traversal of gear teeththereacross and generates a pulse train corresponding to the passage ofgear teeth across the pickup.

The pulse train is fed from the pickup 178 to a pulse shaper 180.

The transmission of electrical signals from the pulse shaper 180 isillustrated in FIG. 6. As indicated in this figure, the pulse shaper.generates a pulse train that is carried by output line 182 to a gate190. The gate is periodically enabled at input 184 by a high speed clock186 having its output line 188 connected to the enable terminal 184 ofthe gate 190. Gate 190 becomes actuated during the interval betweenpulses 193 as shown in FIG. 6a. This interval is defined as 194.Actuation of the gate 190 causes the period counter 192 to incrementallycount during the interval 194. The output 198 of the period counterfeeds a magnitude detector 196. The detector is in essence anintegrating circuit which produces a value dependent upon the intervalor space 194. The magnitude detectorgenerates two output signalsindicating whether a manually set threshold has been detected. Thisthreshold is set by a manual program setter 200 which may be apotentiometer capable of varying the minimum interval 194 for which themagnitude detector 196 will respond. An incremental counter 202 receivestransmission from the magnitude detector 196. If the manuallyprogrammedthreshold for the magnitude detector is not exceeded by the periodcounter 192, a control signal is fed along line 206 from the magnitudedetector 196 to the incremental counter 202 thereby indicating that thecount received from the period counter 192 is less than the threshold.In this event, line 206 is fed to a count terminal of the incrementalcounter which causes this counter 202 to conduct counting. Thecompliment of this condition becomes manifest by a lead 208 whichconnects the output of the magnitude detector 196 with a reset terminalof the incremental counter. Thus, when the period counter 192 informsthe magnitude detector 196 that the interval 194 (FIG. 6a) is not toosmall, the incremental counter 202 becomes reset.

The purpose of the incremental counter 202 is to accumulate a count forsequential intervals 194 that do not exceed the preselected threshold asset in by the manual program setter 200. When the interval 194 is belowthe threshold, this indicates that the teeth on gear 162 (FIG. 5) areaccelerating in their rotation. This indicates a runaway condition inthe Y-axis movement of the load bed.

A manually programmed integrator 212 allows the presetting of a count inthe incremental counter 202 that corresponds to this runaway or unsafecondition. The integrator 212 may for example be a conventionalcomparator which monitors the count in the counter 202 through aninterconnecting lead 204. When the selected count is reached, thecomparator issues a recognition signal 'to the incremental counter 202which thereafter generates an alarm signal on output lead 214 whichdrives an SCR fail-safe drive 216. The output of this drive appears ontransmission leads 1'77 that have been previously illustrated in FIG. 5as the leads connected to a bucking electromagnet 158. in normaloperation of the device, the SCR 216 energizes the bucking electromagnet158 therefor permitting free Y- axis motion of the load bed. However,upon the generation of an alarm signal on lead 214, the transmissionlines 177 cease to carry an energizing signal due to a change of statein the SCR drive 216. As a result, the permanent magnetic brake 154 isactuated to a braking condition thereby preventing descent of the loadbed.

With reference to FIG. 7, reference will be made to anti-bounce circuitoperation along the X-axis as briefly mentioned earlier in relation to86 of FIG. 3. As will be appreciated, identical circuitry will exist forsystem operation along the Y-axis.

Each time a container is to be stored or retrieved, the manual entrymade in position locator 78 (FIG. 3) contains an indication as towhether the container is to be retrieved or stored on the Right or Leftside of an aisle. Referring for the moment to FIG. 3, proximity switches84 and 85 would generate outputs each time a particular proximity switchsenses an associated permanent magnet along the X-axis. The output fromthese switches correspond to circuit input terminals 220 and 222. 226represents the X-axis for counts in the Right direction whereas 222represents X-axis counts in the Left direction. Gate 224 performs an ANDfunction for an input 223, this input being energized when the positionlocator 78 is commanded to store or retrieve a container from a locationon the Right side of an aisle. As previously discussed in connectionwith FIG. 4, the decoder 126 issues an X-Enable signal at a propermoment during an operation cycle. This command signal is carried by lead225. When signals are present on lines 223 and 225, gate 224 performs anAND function and generates an output signal which is fed to an input ofgate 232. An AND function is completed when the X count Right appears atterminal 220. The output from gate 232 is fed to an input terminal ofgate 228. A second gate 226 has a first input thereof connected to thecount enable line 225. A second terminal of gate 226 is connected to alead, 227 that carries a control signal thereon when the positionlocator 78 has been instructed to store or retrieve a container from theLeft side of an aisle. The inputs on lines 225 and 227 are fed to gate226 and an AND function is performed wherein coincidence of inputsignals causes an output signal to be transferred to gate 230. When an Xcount Left signal appears at terminal 222, the gate 230 generates anoutput signal which is communicated to the previously mentioned gate228.

The gate 228 will generate an output signal immediately upon proximityswitch closure associated with either side of an aisle. The output fromgate 228 which performs an OR function feeds an inverter 234 which inturn drives anedge triggered flip-flop 236 by applying a signal at theinput terminal 235. Thus, this first switch closure is stored in theflip-flop, the output terminal 237 of the flip-flop goes low and steersthe edge blockout flip-flop 238 via gate 240. Further operation of thegate 246 will be discussed in greater detail hereinafter. A propagationclockline 242 is provided as an input to the edge lockout flip-flop 238along input lead 248. The propagation clock signal on 242 is out ofsynchronization with the signal appearing at the other input terminal249 connected to the gate 240. The propagation clock signals on 242clock whatever is steered into the lock out flip-flop 238. Thereafter,the output terminal 244 of the edge lock out flip-flop 238 goes low.This output is coupled through lead 246 back to the second terminal ofgate 240. The reason for this is that the edge lock out flip-flop 238must reset the edge detector flip-flop 236. If the steering gate 240 isnot held, the next input to the edge lock out flip-flop 238 will resetit. d

When the binary state on the propagation clock line 242 changes, gate256 performs an AND function. The

signal is generated at the output of gate 256) which is transmittedalong lead 252 to gate 256. An OR function is performed by this gatethereby generating an output signal on lead 258 which resets the edgedetector flip-flop 236. This causes a change in the state at output line237 of the flip-flop 236 and removes the holding input on gate 240.

As will be appreciated, the primary function of the just discussedcircuitry is to recognize an initial proximity switch closure bydetecting the leading edge of the first switch closure. Trailing edgesand other spurious leading edges are disregarded by virtue of thediscussed holding action by gate 240 in conjunction with flipflops 236and 238. This holding or locking out of pulse edges other than the firstleading edge (original switch closure) terminates when the proximityswitches cease to generate output signals for a short period of timeindicating that bouncing has stopped. Thereafter, in an identicalfashion, switch closure will be recognized by detection of the firstleading edge by flip-flop 236. All other trailing edges of switchsignals produced by bouncing are eliminated by the edge lockoutflip-flop 238.

Simultaneous with the clocking of flip-flop 236, a third flip-flop 262has a clock signal applied thereto along lead 264. As will be discussedhereinafter, the purpose of this flip-flop in conjunction with othercircuitry is to recognize the bounce occurring at the leading edge ofthe proximity switch closure. The signal appearing on lead 362 steersthe flip-flop 262. The clock signal on lead 264 is characterized as abounce clock signal. The period of the bounce clock signal ispreselected to be slightly less than the period of an average bouncesignal. At any time the input proximity switch lines become actuated at226 or 222, and the bounce clock signal is set high, the flip-flop 262is set. Not only is the flip-flop 262 steered by a switch closure, thegate 266 feeds gate 268 which causes reset of the flip-flop 262. Thus,if a proximity switch gives a temporary closure, and is followed by anopening of the switch, there will be a DC reset of flip-flop 262 if asignal on the bounce clock line 264 is coincident therewith. However,finally an activated proximity switch will settle down and there will bepresent a high steering input, and a bounce clock signal comes along onlead 264, the switch closure will not cause the flip-tlop 262 to bereset. As this occurs, the bouncing clock signal at lead 264 presentsitself along connecting lead 276 to a gate 272. With flip-flop 262 setfrom switch closure coincident with a bounce clock signal on 264, theflip-flop output 262 will be low on lead 276. This occurrence permits afirst input terminal of gate 272 to be enabled by a lead 276.

The occurrence of a clock signal on line 264 enables the second terminalof gate 272 via lead 276. The output from gate 272 goes high and setsthe flip-flop 286 comprising gates 280 and 288. As will be seen fromFIG. 7, the high output on lead 278 feeds one terminal of gate 280. Itis noted that the flip-flop 266 functions as another look out flip-flop.With the flip-flop 286 being set, a true output is derived along lead282. This line goes low and presents a low signal to the input terminal287 of the edge detector flipflop 236. The output of gate 288 goes highwhen the flip-flop 286 is set. The output line of gate 238 being highgoes through an OR gate 290 which causes the DC reset of the edge lockout flip-flop 238 via connecting lead 292. This removes the DC resetfrom flip-flop 236. Thus, the flipflop 236 can be held in a resetcondition by inhibiting terminal 287. The output terminal 284 offlip-flop 286 is connected to a lead 314 which transmits the output fromterminal 284 to the reset terminal of flip-flop 262 via gates 266 and263. This inhibits the count switch opening from resetting the lock outflip-flop 262. Otherwise stated the reset path to flip-flop 262 whichincludes gates 266 and 268 is inhibited. At the same time, the input ofgate 294i is steered via lead 296. The output line 298 of gate 29d feedsdirectly to a preset input terminal 306 of the flip-flop 262. This meansthat if an input count switch is closed, gate 294 has two high inputs,it is enabled thereby presetting flip-flop 262 along line 298, at thepreset terminal 360. Thus far, the circuitry has functioned to recognizea switch closure; storage of the leading edge; lock out of other pulseedges; recognizing the finishing of bouncing of the initial leading edgeand cessation of bouncing. At this point, the steering in theanti-bounce circuitry is turned around so that the circuitry "isprepared to detect a clean opening of the switch. When a proximityswitch first opens, gate 234 is inhibited because its input along line302 goes low therefore inhibiting the gate 294 from presetting theflip-flop 262 at terminal 300. However, the input of flip-flop 262 alongline 364 is steered. Any spurious operation of a proximity switch willbe recognized as a high output along line 362. If this happens again,the flip-flop 262 is preset. if however, the proximity switch asdetected at line 302 remains low, long enough for the clock on line 264to clock flip-flop 262 low, and for the proximity switch to remain openlong enough for the output of the flip-flop 262 (which has a low outputon line 306) coincidence can be effected at gate 308 fed with a clocksignal via lead 274. When this coincidence occurs, an output isgenerated on line 310 thereby presenting an input to gate 288 whichresets the flip-flop 286. The output 284 changes to a low state andresets the entire circuitry to its original state. At this point, thecircuitry is armed to detect the leading edge of another switch closure.More precisely, this occurs when the low output on lead 312 is presentthereby removing the reset hold on flip-flop 238 through the gated pathincluding gate 296 and lead 292.

The change along lead 3% is also used to enable gate 266 whileinhibiting gate 294. The output of gate 280 if carried by lead 282reverts to its high state. it being high returns high steering attheoriginal flip-flop 236 so that it is prepared to recognize the nextleading edge at a switch closure.

The output of flip-flop 266 is presented along lead 316 to a lamp driver31% which in turn drives a lamp terminal 321. A resistor 326) isconnected between the terminal 321i and ground. The purpose of thisresistor is to limit surge currents which would otherwise injure driver3118 due to the cold filament of a lamp connected to terminal 321.

Each time the flip-flop 236 is set, an output signal is presented to afirst terminal of gate 322. The second terminal of this gate isconnected through lead 324 to a control signal representing the absenceof coincidence between the selected X coordinate and the instantaneous Xcoordinate of the machine. The control signal indicating the lack of Xcoincidence is derived from the comparator 66 shown in FIG. 3. Theoutput from gate 322 is carried by lead 328 which generates an up countsignal to the counter 82 shown in FIG. 3. The output lead 326 offlip-flop 236 is connected in parallel with an input terminal to gate346. The second terminal of this gate is connected to a control line 324which becomes energized when coincidence does exist between the selectedX coordinate as set in the position locator 78 (H6. 3) and theinstantaneous position of the load bed. When gate 346 is actuated byvirtue of X coordinate coincidence, a signal appears on output line 343to present a down count for counter 82 (FIG. 3). When this coincidenceoccurs, gate 322 is inhibited.

FlG. 8 illustrates timing diagrams plotted for critical points in thecircuit of MG. 7. The first wave form illustrates electrical signalsderived from switch closures as presented on line 362 in FIG. 7.

The second timing diagram indicates the output signals on line 326 (HO.7) from flip-flop 236.

The third timing diagram indicates a pulse train which represents thepropagation cloclr signal along line 242.

The fourth timing diagram represents the inverse of the signal appearingon line 244 which is connected to the edge lock out flip-flop 238.During the width of the pulse shown in the fourth timing diagram, theedge detecting flip-flop 236 is disarrned. Actually, it is this pulsewidth which sets the minimum width for the output of edge detector 236(at line 326).

The fifth timing diagram indicates the pulse train that is the bounceclock signal at line 264.

The sixth timing diagram represents the output of flip-flop 262, alonglead 366.

The seventh timing diagram represents the output from flip-flop 286along line 3112. The width of the pulse indicated in this timing diagramdisarms the edge detector flip-flop 236.

FIG. 9 illustrates a block diagram for the multiple location Spanfeature of the present invention. With regard to FIG. 41, the previousdiscussion mentioned the function of the Span circuitry 1152. To brieflyreview, the Span circuitry maximizes the efiiciency of the machine.During a retrieval process, if the load bed is directed to a firstlocation and that location is empty, the Span circuitry automaticallydirects the load bed to move to an adjacent location for retrieval of acontainer which would contain the same material as the originallyselected container. in the event the second location is also empty, theSpan circuitry could repeat the process thereby moving the load bed to athird location, and so on. A similar operation would take place duringstorage. Thus, if a first location is chosen for return of a container,and that position is found to already house a container, the Spancircuitry can come into play and cause the load bed to move to anadjacent location where the procedure is repeated until an availablelocation is found.

Returning to H0. 9, the particular block circuitry of the Span system isillustrated. Considering this system in detail, reference is made to Flt9 wherein the position locator 73, previously discussed in connectionwith FlG. 3, is illustrated. Actually, the position locator includes acompartment location switch entry 333 and a separate entry 337 thatdictates the extent to which the system of FIG. 9 will span multiplelocations. To be more explicit, the switch output from locator portion33? forms an up count switch input to an up-down counter 332. Thiscounter will finally assume the count that is entered in the positionlocator section 337. if, by

way of example, the counter 332 stores the count equivalent to two, thismeans that when the load bed of the machine comes to an originallocation as specified by position locator section 338, if there is nocontainer present thereat, the system willmake two additional attemptsto find a container at adjacent locations.

In sequence, the original location of a container as entered in positionlocator section 338 will provide a first input to a comparator 340 vialead 342. A main storage register 336 is sequentially triggered withupcounts from lead 344 which corresponds to line 328 of the anti-bouncecircuitry of FIG. 7. The main register serves as a count accumulator andwhen there is coincidence between the count in the main register 336 andthe selected location as entered in the position locator 78, the loadbed has come to its original selected position. The comparator 340 hastwo outputs. The first output 324 carries a signal when coincidence isreached. The line 324' carries a signal indicating lack of coincidence.As mentioned in the previous discussion of the anti-bounce circuit (FIG.7) when coincidence occurs, up count is inhibited. However, under suchcircumstances a down count along lead 348 can be obtained from gate 346(FIG. 7).

Assuming a load bed comes to rest at the original selected location, andno container is present for retrieval, photoelectric means 153 (FIG. 4)alert the system to this fact. A decoder 334 is intermediately connectedbetween the counter 332 and a display 329. The display 329 indicatesvisually the condition of counter 332. Also, an output line 350 providesinformation to the circuitry of FIG. 4 (at 152) to condition thecircuitry of FIG. 4 for performing a span operation. This means, that ifthe machine is to span an adjacent location along the X-axis, thepresence of a number other than in the decoder 334 provides informationfor the circuitry of FIG. 4 thereby causing this circuitry to initiatemotor operation of the system to an adjacent location on the X-axis.Each time the load bed is moved to an adjacent location from thepreviously attempted location, the counter 332 will be counted downuntil the decoder 334 recognizes the presence of a 0 count in thecounter 332. At this time, the circuitry of FIG. 4 will operate toreturn the machine to its home station. If the operation is to bestopped in the middle of a span procedure, a clear switch 352 isprovided to reset the counter 332 to O.

The display 329 provides valuable information to personnel. For example,if an entry is made in position locator 78 directing the Span circuitryto search three additional locations other than the originally selectedone, should a container be absent in the original location, the display329 will indicate how many additional locations (up to 3) had tobeattempted before a container was found. This gives personnel valuableinformation as to how many of the three alternate (span) positions stillhouse containers. Accordingly, without having to manually check thepresence of containers in these alternate locations, personnel have theopportunity for checking inventory in this manner.

A number of safety devices lend themselves to the present invention. Forexample, photoelectric devices 153 (FIG. 3) are be employed to detecteither the absence or presence of a container in a particular racklocation. Thus, during a storage operation, should a container be in aselected position, a photoelectric detector can provide this informationand preclude the possibility of crushing an unloading container into anoccupied location. Similarly, lost motion can be prevented by detectingthe absence of a container in a location that has been selected. Thisobviates the necessity for the electromagnetic unit (FIG. 2) from movingtoward engagement with an absent container.

Another safeguard is a photoelectric sensing device for detecting theactual presence of a container on the load bed. Thus, during a storingoperation, if an operator has forgotten to place a container on the loadbed, the machine will not go through a wasted operational cycle.Likewise, if a retrieval operation is to be performed, the photoelectricdevice can insure that the load bed is free of another container.

It should be emphasized that although electromagnetic attraction ofcontainers is used to manipulate the containers on and off the bed, itis equally desirable to substitute a movable fork member for theelectromagnet so that pallets can be manipulated as the containers.

It should be understood that the invention is not limited to the exactdetails of construction shown and described herein for obviousmodifications will occur to persons skilled in the art.

What we claim is:

1. In an automated material storage and retrieval system which includesa rack assembly, a frame movably mounted-to said rack assembly forpermitting horizontal movement thereof, a load bed vertically movable onthe frame, the combined movements of the frame and load bed effectingdisplacement of the load bed to a preselected location on said rackassembly and load handling means mounted on the load bed fortransferring loads relative to the load bed, further wherein drive meansare provided to render the horizontal and vertical movements, acondition response apparatus for determining load bed locationcomprising:

a control unit mounted on said frame;

position indicator means mounted to the rack assembly for indicatinghorizontal and vertical position locations on the rack assembly;

means mounted on said movable frame and opera tively associated withsaid position indicator means for sensing horizontal and verticalmovement of the frame and load bed relative to the rack assembly andgenerating a plurality of discrete signals as a result thereof tocontrol said drive means;

means connected to the sensing means for selecting and verifyingpreselected one of said signals generated therefrom to control saiddrive means to position said frame at a preselected location on saidrack assembly;

said control unit including means for entering a span count and for alsopreselecting a load transfer the first preselected load transferoperation.

2. The subject matter recited in claim 1 together with display meansconnected in circuit with the output of the counter means for visuallydisplaying the count in the counter means thus informing an operator asto the number of times the system had to make alternate attempts atcompleting the selected transfer operation.

1. In an automated material storage and retrieval system which includes a rack assembly, a frame movably mounted to said rack assembly for permitting horizontal movement thereof, a load bed vertically movable on the frame, the combined movements of the frame and load bed effecting displacement of the load bed to a preselected location on said rack assembly and load handling means mounted on the load bed for transferring loads relative to the load bed, further wherein drive means are provided to render the horizontal and vertical movements, a condition response apparatus for determining load bed location comprising: a control unit mounted on said frame; position indicator means mounted to the rack assembly for indicating horizontal and vertical position locations on the rack assembly; means mounted on said movable frame and operatively associated with said position indicator means for sensing horizontal and vertical movement of the frame and load bed relative to the rack assembly and generating a plurality of discrete signals as a result thereof to control said drive means; means connected to the sensing means for selecting and verifying preselected one of said signals generated therefrom to control said drive means to position said frame at a preselected location on said rack assembly; said control unit including means for entering a span count and for also preselecting a load transfer operation at a preselected storage location; comparison means with inputs connected to the entering means and the selecting and verifying means for energizing the drive means until the load bed arrives at the preselected location; means with an output for determining if the preselected transfer operation can be performed at the preselected locations; span means connected to the output of said determining means for actuating the drive means to effect movement of the load bed only to a predetermined number of successive immediate adjacent predetermined locations relative to said first preselected storage location in the event that the preselected transfer operation cannot be performed at the first preselected location; numerical counter means with an output connected to the span means for limiting and controlling, to the span count, the number of successive attempts made at said immediate adjacent predetermined locations by the span means in an effort to perform the first preselected load transfer operation.
 2. The subject matter recited in claim 1 together with display means connected in circuit with the output of the counter means for visually displaying the count in the counter means thus informing an operator as to the number of times the system had to make alternate attempts at completing the selected transfer operation. 